1. Field of the Invention
The present invention relates to an automotive headlamp apparatus, in particular, to a structure of an automotive headlamp apparatus that forms multiple types of light distribution patterns using shades.
2. Description of the Related Art
An automotive headlamp apparatus is designed to emit a low-beam or a high-beam by emitting a light from a light source in the automotive front direction through a projection lens. Light distribution patterns of emitted beams are different from each other between the low-beam and the high-beam. There are known so-called four-lamp type and fixed light distribution type headlamps that perform switching between the low-beam and the high-beam by switching on/off the light sources for a low-beam and a high-beam. Also, there are known so-called two-lamp type and variable light distribution type headlamps that form a light distribution pattern for a low-beam by shielding part of the beam emitted from a light source, while form that for a high-beam when not shielding any part of the beam.
Recently, with progress toward high-performance and high-functionality in vehicles, headlamps apparatus thereof are required so as to be capable of forming light distribution patterns to deal with various situations. In particular, the high-beam has a possibility of providing a dazzle entailing a sense of discomfort, so-called a “glare”, to an oncoming vehicle, pedestrian, preceding vehicle or the like; and therefore the high-beam is apt to be withheld from use when an oncoming vehicle, pedestrian, preceding vehicle or the like is present, resulting in low usage frequency of the high-beam. On the other hand, the high-beam has an effect of improving forward visibility of a driver, and hence the high-beam is required so as to form a light distribution pattern without providing a glare. To meet such a demand, for example, Japanese Patent Application Publication No. 2007-179969 discloses a structure in which a light distribution pattern of the high-beam can be changed. In the structure, a plurality of light sources are installed in a headlamp apparatus for a high-beam such that a light distribution pattern can be changed in shape by controlling switching on/off of the light sources.
The automotive headlamp apparatus for a high-beam disclosed in the above Japanese Patent Application Publication No. 2007-179969 is capable of optimally setting a high-beam emitting region in accordance with presence or absence of a pedestrian, preceding vehicle or oncoming vehicle, and is effective as a structure for forming an optimal light distribution pattern for a high-beam. However, there is room for improvement in terms of cost and control system, and therefore a technique is required to be developed in which the high-beam emitting region is optimized with a simpler structure and a simpler control system, in the same way as the structure disclosed in the above Japanese Patent Application Publication No. 2007-179969.